/* Target-dependent code for GDB, the GNU debugger.
- Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000
- Free Software Foundation, Inc.
+
+ Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996,
+ 1997, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
This file is part of GDB.
#include "gdbcmd.h"
#include "symfile.h"
#include "objfiles.h"
+#include "regcache.h"
+#include "value.h"
+#include "osabi.h"
+
+#include "solib-svr4.h"
+#include "ppc-tdep.h"
+
+/* The following instructions are used in the signal trampoline code
+ on GNU/Linux PPC. The kernel used to use magic syscalls 0x6666 and
+ 0x7777 but now uses the sigreturn syscalls. We check for both. */
+#define INSTR_LI_R0_0x6666 0x38006666
+#define INSTR_LI_R0_0x7777 0x38007777
+#define INSTR_LI_R0_NR_sigreturn 0x38000077
+#define INSTR_LI_R0_NR_rt_sigreturn 0x380000AC
-/* The following two instructions are used in the signal trampoline
- code on linux/ppc */
-#define INSTR_LI_R0_0x7777 0x38007777
-#define INSTR_SC 0x44000002
+#define INSTR_SC 0x44000002
/* Since the *-tdep.c files are platform independent (i.e, they may be
used to build cross platform debuggers), we can't include system
#define PPC_LINUX_PT_FPR31 (PPC_LINUX_PT_FPR0 + 2*31)
#define PPC_LINUX_PT_FPSCR (PPC_LINUX_PT_FPR0 + 2*32 + 1)
-int ppc_linux_at_sigtramp_return_path (CORE_ADDR pc);
+static int ppc_linux_at_sigtramp_return_path (CORE_ADDR pc);
/* Determine if pc is in a signal trampoline...
- Ha! That's not what this does at all. wait_for_inferior in infrun.c
- calls IN_SIGTRAMP in order to detect entry into a signal trampoline
- just after delivery of a signal. But on linux, signal trampolines
- are used for the return path only. The kernel sets things up so that
- the signal handler is called directly.
+ Ha! That's not what this does at all. wait_for_inferior in
+ infrun.c calls PC_IN_SIGTRAMP in order to detect entry into a
+ signal trampoline just after delivery of a signal. But on
+ GNU/Linux, signal trampolines are used for the return path only.
+ The kernel sets things up so that the signal handler is called
+ directly.
If we use in_sigtramp2() in place of in_sigtramp() (see below)
we'll (often) end up with stop_pc in the trampoline and prev_pc in
first instruction long after the fact, just in case the observed
behavior is ever fixed.)
- IN_SIGTRAMP is called from blockframe.c as well in order to set
- the signal_handler_caller flag. Because of our strange definition
- of in_sigtramp below, we can't rely on signal_handler_caller getting
- set correctly from within blockframe.c. This is why we take pains
- to set it in init_extra_frame_info(). */
+ PC_IN_SIGTRAMP is called from blockframe.c as well in order to set
+ the frame's type (if a SIGTRAMP_FRAME). Because of our strange
+ definition of in_sigtramp below, we can't rely on the frame's type
+ getting set correctly from within blockframe.c. This is why we
+ take pains to set it in init_extra_frame_info().
+
+ NOTE: cagney/2002-11-10: I suspect the real problem here is that
+ the get_prev_frame() only initializes the frame's type after the
+ call to INIT_FRAME_INFO. get_prev_frame() should be fixed, this
+ code shouldn't be working its way around a bug :-(. */
int
ppc_linux_in_sigtramp (CORE_ADDR pc, char *func_name)
char buf[4];
CORE_ADDR handler;
- lr = read_register (LR_REGNUM);
+ lr = read_register (gdbarch_tdep (current_gdbarch)->ppc_lr_regnum);
if (!ppc_linux_at_sigtramp_return_path (lr))
return 0;
return (pc == handler || pc == handler + 4);
}
+static int
+insn_is_sigreturn (unsigned long pcinsn)
+{
+ switch(pcinsn)
+ {
+ case INSTR_LI_R0_0x6666:
+ case INSTR_LI_R0_0x7777:
+ case INSTR_LI_R0_NR_sigreturn:
+ case INSTR_LI_R0_NR_rt_sigreturn:
+ return 1;
+ default:
+ return 0;
+ }
+}
+
/*
* The signal handler trampoline is on the stack and consists of exactly
* two instructions. The easiest and most accurate way of determining
* instructions. It'd be faster though if we could find a way to do this
* via some simple address comparisons.
*/
-int
+static int
ppc_linux_at_sigtramp_return_path (CORE_ADDR pc)
{
char buf[12];
pcinsn = extract_unsigned_integer (buf + 4, 4);
return (
- (pcinsn == INSTR_LI_R0_0x7777
+ (insn_is_sigreturn (pcinsn)
&& extract_unsigned_integer (buf + 8, 4) == INSTR_SC)
||
(pcinsn == INSTR_SC
- && extract_unsigned_integer (buf, 4) == INSTR_LI_R0_0x7777));
+ && insn_is_sigreturn (extract_unsigned_integer (buf, 4))));
}
-CORE_ADDR
+static CORE_ADDR
ppc_linux_skip_trampoline_code (CORE_ADDR pc)
{
char buf[4];
/* Get address of the relocation entry (Elf32_Rela) */
if (target_read_memory (plt_table + reloc_index, buf, 4) != 0)
return 0;
- reloc = extract_address (buf, 4);
+ reloc = extract_unsigned_integer (buf, 4);
sect = find_pc_section (reloc);
if (!sect)
/* The rs6000 version of FRAME_SAVED_PC will almost work for us. The
signal handler details are different, so we'll handle those here
and call the rs6000 version to do the rest. */
-unsigned long
+CORE_ADDR
ppc_linux_frame_saved_pc (struct frame_info *fi)
{
- if (fi->signal_handler_caller)
+ if ((get_frame_type (fi) == SIGTRAMP_FRAME))
{
CORE_ADDR regs_addr =
- read_memory_integer (fi->frame + PPC_LINUX_REGS_PTR_OFFSET, 4);
+ read_memory_integer (get_frame_base (fi)
+ + PPC_LINUX_REGS_PTR_OFFSET, 4);
/* return the NIP in the regs array */
return read_memory_integer (regs_addr + 4 * PPC_LINUX_PT_NIP, 4);
}
- else if (fi->next && fi->next->signal_handler_caller)
+ else if (get_next_frame (fi)
+ && (get_frame_type (get_next_frame (fi)) == SIGTRAMP_FRAME))
{
CORE_ADDR regs_addr =
- read_memory_integer (fi->next->frame + PPC_LINUX_REGS_PTR_OFFSET, 4);
+ read_memory_integer (get_frame_base (get_next_frame (fi))
+ + PPC_LINUX_REGS_PTR_OFFSET, 4);
/* return LNK in the regs array */
return read_memory_integer (regs_addr + 4 * PPC_LINUX_PT_LNK, 4);
}
{
rs6000_init_extra_frame_info (fromleaf, fi);
- if (fi->next != 0)
+ if (get_next_frame (fi) != 0)
{
/* We're called from get_prev_frame_info; check to see if
this is a signal frame by looking to see if the pc points
at trampoline code */
- if (ppc_linux_at_sigtramp_return_path (fi->pc))
- fi->signal_handler_caller = 1;
+ if (ppc_linux_at_sigtramp_return_path (get_frame_pc (fi)))
+ deprecated_set_frame_type (fi, SIGTRAMP_FRAME);
else
- fi->signal_handler_caller = 0;
+ /* FIXME: cagney/2002-11-10: Is this double bogus? What
+ happens if the frame has previously been marked as a dummy? */
+ deprecated_set_frame_type (fi, NORMAL_FRAME);
}
}
{
/* We'll find the wrong thing if we let
rs6000_frameless_function_invocation () search for a signal trampoline */
- if (ppc_linux_at_sigtramp_return_path (fi->pc))
+ if (ppc_linux_at_sigtramp_return_path (get_frame_pc (fi)))
return 0;
else
return rs6000_frameless_function_invocation (fi);
void
ppc_linux_frame_init_saved_regs (struct frame_info *fi)
{
- if (fi->signal_handler_caller)
+ if ((get_frame_type (fi) == SIGTRAMP_FRAME))
{
CORE_ADDR regs_addr;
int i;
- if (fi->saved_regs)
+ if (get_frame_saved_regs (fi))
return;
frame_saved_regs_zalloc (fi);
regs_addr =
- read_memory_integer (fi->frame + PPC_LINUX_REGS_PTR_OFFSET, 4);
- fi->saved_regs[PC_REGNUM] = regs_addr + 4 * PPC_LINUX_PT_NIP;
- fi->saved_regs[PS_REGNUM] = regs_addr + 4 * PPC_LINUX_PT_MSR;
- fi->saved_regs[CR_REGNUM] = regs_addr + 4 * PPC_LINUX_PT_CCR;
- fi->saved_regs[LR_REGNUM] = regs_addr + 4 * PPC_LINUX_PT_LNK;
- fi->saved_regs[CTR_REGNUM] = regs_addr + 4 * PPC_LINUX_PT_CTR;
- fi->saved_regs[XER_REGNUM] = regs_addr + 4 * PPC_LINUX_PT_XER;
- fi->saved_regs[MQ_REGNUM] = regs_addr + 4 * PPC_LINUX_PT_MQ;
+ read_memory_integer (get_frame_base (fi)
+ + PPC_LINUX_REGS_PTR_OFFSET, 4);
+ get_frame_saved_regs (fi)[PC_REGNUM] = regs_addr + 4 * PPC_LINUX_PT_NIP;
+ get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_ps_regnum] =
+ regs_addr + 4 * PPC_LINUX_PT_MSR;
+ get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_cr_regnum] =
+ regs_addr + 4 * PPC_LINUX_PT_CCR;
+ get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_lr_regnum] =
+ regs_addr + 4 * PPC_LINUX_PT_LNK;
+ get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_ctr_regnum] =
+ regs_addr + 4 * PPC_LINUX_PT_CTR;
+ get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_xer_regnum] =
+ regs_addr + 4 * PPC_LINUX_PT_XER;
+ get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_mq_regnum] =
+ regs_addr + 4 * PPC_LINUX_PT_MQ;
for (i = 0; i < 32; i++)
- fi->saved_regs[GP0_REGNUM + i] = regs_addr + 4 * PPC_LINUX_PT_R0 + 4 * i;
+ get_frame_saved_regs (fi)[gdbarch_tdep (current_gdbarch)->ppc_gp0_regnum + i] =
+ regs_addr + 4 * PPC_LINUX_PT_R0 + 4 * i;
for (i = 0; i < 32; i++)
- fi->saved_regs[FP0_REGNUM + i] = regs_addr + 4 * PPC_LINUX_PT_FPR0 + 8 * i;
+ get_frame_saved_regs (fi)[FP0_REGNUM + i] = regs_addr + 4 * PPC_LINUX_PT_FPR0 + 8 * i;
}
else
rs6000_frame_init_saved_regs (fi);
ppc_linux_frame_chain (struct frame_info *thisframe)
{
/* Kernel properly constructs the frame chain for the handler */
- if (thisframe->signal_handler_caller)
- return read_memory_integer ((thisframe)->frame, 4);
+ if ((get_frame_type (thisframe) == SIGTRAMP_FRAME))
+ return read_memory_integer (get_frame_base (thisframe), 4);
else
return rs6000_frame_chain (thisframe);
}
-/* FIXME: Move the following to rs6000-tdep.c (or some other file where
- it may be used generically by ports which use either the SysV ABI or
- the EABI */
+/* ppc_linux_memory_remove_breakpoints attempts to remove a breakpoint
+ in much the same fashion as memory_remove_breakpoint in mem-break.c,
+ but is careful not to write back the previous contents if the code
+ in question has changed in between inserting the breakpoint and
+ removing it.
+
+ Here is the problem that we're trying to solve...
+
+ Once upon a time, before introducing this function to remove
+ breakpoints from the inferior, setting a breakpoint on a shared
+ library function prior to running the program would not work
+ properly. In order to understand the problem, it is first
+ necessary to understand a little bit about dynamic linking on
+ this platform.
+
+ A call to a shared library function is accomplished via a bl
+ (branch-and-link) instruction whose branch target is an entry
+ in the procedure linkage table (PLT). The PLT in the object
+ file is uninitialized. To gdb, prior to running the program, the
+ entries in the PLT are all zeros.
+
+ Once the program starts running, the shared libraries are loaded
+ and the procedure linkage table is initialized, but the entries in
+ the table are not (necessarily) resolved. Once a function is
+ actually called, the code in the PLT is hit and the function is
+ resolved. In order to better illustrate this, an example is in
+ order; the following example is from the gdb testsuite.
+
+ We start the program shmain.
+
+ [kev@arroyo testsuite]$ ../gdb gdb.base/shmain
+ [...]
+
+ We place two breakpoints, one on shr1 and the other on main.
+
+ (gdb) b shr1
+ Breakpoint 1 at 0x100409d4
+ (gdb) b main
+ Breakpoint 2 at 0x100006a0: file gdb.base/shmain.c, line 44.
+
+ Examine the instruction (and the immediatly following instruction)
+ upon which the breakpoint was placed. Note that the PLT entry
+ for shr1 contains zeros.
+
+ (gdb) x/2i 0x100409d4
+ 0x100409d4 <shr1>: .long 0x0
+ 0x100409d8 <shr1+4>: .long 0x0
+
+ Now run 'til main.
+
+ (gdb) r
+ Starting program: gdb.base/shmain
+ Breakpoint 1 at 0xffaf790: file gdb.base/shr1.c, line 19.
+
+ Breakpoint 2, main ()
+ at gdb.base/shmain.c:44
+ 44 g = 1;
+
+ Examine the PLT again. Note that the loading of the shared
+ library has initialized the PLT to code which loads a constant
+ (which I think is an index into the GOT) into r11 and then
+ branchs a short distance to the code which actually does the
+ resolving.
+
+ (gdb) x/2i 0x100409d4
+ 0x100409d4 <shr1>: li r11,4
+ 0x100409d8 <shr1+4>: b 0x10040984 <sg+4>
+ (gdb) c
+ Continuing.
+
+ Breakpoint 1, shr1 (x=1)
+ at gdb.base/shr1.c:19
+ 19 l = 1;
+
+ Now we've hit the breakpoint at shr1. (The breakpoint was
+ reset from the PLT entry to the actual shr1 function after the
+ shared library was loaded.) Note that the PLT entry has been
+ resolved to contain a branch that takes us directly to shr1.
+ (The real one, not the PLT entry.)
+
+ (gdb) x/2i 0x100409d4
+ 0x100409d4 <shr1>: b 0xffaf76c <shr1>
+ 0x100409d8 <shr1+4>: b 0x10040984 <sg+4>
+
+ The thing to note here is that the PLT entry for shr1 has been
+ changed twice.
+
+ Now the problem should be obvious. GDB places a breakpoint (a
+ trap instruction) on the zero value of the PLT entry for shr1.
+ Later on, after the shared library had been loaded and the PLT
+ initialized, GDB gets a signal indicating this fact and attempts
+ (as it always does when it stops) to remove all the breakpoints.
+
+ The breakpoint removal was causing the former contents (a zero
+ word) to be written back to the now initialized PLT entry thus
+ destroying a portion of the initialization that had occurred only a
+ short time ago. When execution continued, the zero word would be
+ executed as an instruction an an illegal instruction trap was
+ generated instead. (0 is not a legal instruction.)
+
+ The fix for this problem was fairly straightforward. The function
+ memory_remove_breakpoint from mem-break.c was copied to this file,
+ modified slightly, and renamed to ppc_linux_memory_remove_breakpoint.
+ In tm-linux.h, MEMORY_REMOVE_BREAKPOINT is defined to call this new
+ function.
+
+ The differences between ppc_linux_memory_remove_breakpoint () and
+ memory_remove_breakpoint () are minor. All that the former does
+ that the latter does not is check to make sure that the breakpoint
+ location actually contains a breakpoint (trap instruction) prior
+ to attempting to write back the old contents. If it does contain
+ a trap instruction, we allow the old contents to be written back.
+ Otherwise, we silently do nothing.
+
+ The big question is whether memory_remove_breakpoint () should be
+ changed to have the same functionality. The downside is that more
+ traffic is generated for remote targets since we'll have an extra
+ fetch of a memory word each time a breakpoint is removed.
+
+ For the time being, we'll leave this self-modifying-code-friendly
+ version in ppc-linux-tdep.c, but it ought to be migrated somewhere
+ else in the event that some other platform has similar needs with
+ regard to removing breakpoints in some potentially self modifying
+ code. */
+int
+ppc_linux_memory_remove_breakpoint (CORE_ADDR addr, char *contents_cache)
+{
+ const unsigned char *bp;
+ int val;
+ int bplen;
+ char old_contents[BREAKPOINT_MAX];
-/* round2 rounds x up to the nearest multiple of s assuming that s is a
- power of 2 */
+ /* Determine appropriate breakpoint contents and size for this address. */
+ bp = BREAKPOINT_FROM_PC (&addr, &bplen);
+ if (bp == NULL)
+ error ("Software breakpoints not implemented for this target.");
+
+ val = target_read_memory (addr, old_contents, bplen);
+
+ /* If our breakpoint is no longer at the address, this means that the
+ program modified the code on us, so it is wrong to put back the
+ old value */
+ if (val == 0 && memcmp (bp, old_contents, bplen) == 0)
+ val = target_write_memory (addr, contents_cache, bplen);
-#undef round2
-#define round2(x,s) ((((long) (x) - 1) & ~(long)((s)-1)) + (s))
+ return val;
+}
-/* Pass the arguments in either registers, or in the stack. Using the
- ppc sysv ABI, the first eight words of the argument list (that might
- be less than eight parameters if some parameters occupy more than one
- word) are passed in r3..r10 registers. float and double parameters are
- passed in fpr's, in addition to that. Rest of the parameters if any
- are passed in user stack.
+/* Fetch (and possibly build) an appropriate link_map_offsets
+ structure for GNU/Linux PPC targets using the struct offsets
+ defined in link.h (but without actual reference to that file).
- If the function is returning a structure, then the return address is passed
- in r3, then the first 7 words of the parametes can be passed in registers,
- starting from r4. */
+ This makes it possible to access GNU/Linux PPC shared libraries
+ from a GDB that was not built on an GNU/Linux PPC host (for cross
+ debugging). */
-CORE_ADDR
-ppc_sysv_abi_push_arguments (nargs, args, sp, struct_return, struct_addr)
- int nargs;
- value_ptr *args;
- CORE_ADDR sp;
- int struct_return;
- CORE_ADDR struct_addr;
+struct link_map_offsets *
+ppc_linux_svr4_fetch_link_map_offsets (void)
+{
+ static struct link_map_offsets lmo;
+ static struct link_map_offsets *lmp = NULL;
+
+ if (lmp == NULL)
+ {
+ lmp = &lmo;
+
+ lmo.r_debug_size = 8; /* The actual size is 20 bytes, but
+ this is all we need. */
+ lmo.r_map_offset = 4;
+ lmo.r_map_size = 4;
+
+ lmo.link_map_size = 20; /* The actual size is 560 bytes, but
+ this is all we need. */
+ lmo.l_addr_offset = 0;
+ lmo.l_addr_size = 4;
+
+ lmo.l_name_offset = 4;
+ lmo.l_name_size = 4;
+
+ lmo.l_next_offset = 12;
+ lmo.l_next_size = 4;
+
+ lmo.l_prev_offset = 16;
+ lmo.l_prev_size = 4;
+ }
+
+ return lmp;
+}
+
+
+/* Macros for matching instructions. Note that, since all the
+ operands are masked off before they're or-ed into the instruction,
+ you can use -1 to make masks. */
+
+#define insn_d(opcd, rts, ra, d) \
+ ((((opcd) & 0x3f) << 26) \
+ | (((rts) & 0x1f) << 21) \
+ | (((ra) & 0x1f) << 16) \
+ | ((d) & 0xffff))
+
+#define insn_ds(opcd, rts, ra, d, xo) \
+ ((((opcd) & 0x3f) << 26) \
+ | (((rts) & 0x1f) << 21) \
+ | (((ra) & 0x1f) << 16) \
+ | ((d) & 0xfffc) \
+ | ((xo) & 0x3))
+
+#define insn_xfx(opcd, rts, spr, xo) \
+ ((((opcd) & 0x3f) << 26) \
+ | (((rts) & 0x1f) << 21) \
+ | (((spr) & 0x1f) << 16) \
+ | (((spr) & 0x3e0) << 6) \
+ | (((xo) & 0x3ff) << 1))
+
+/* Read a PPC instruction from memory. PPC instructions are always
+ big-endian, no matter what endianness the program is running in, so
+ we can't use read_memory_integer or one of its friends here. */
+static unsigned int
+read_insn (CORE_ADDR pc)
{
- int argno;
- int greg, freg;
- int argstkspace;
- int structstkspace;
- int argoffset;
- int structoffset;
- value_ptr arg;
- struct type *type;
- int len;
- char old_sp_buf[4];
- CORE_ADDR saved_sp;
-
- greg = struct_return ? 4 : 3;
- freg = 1;
- argstkspace = 0;
- structstkspace = 0;
-
- /* Figure out how much new stack space is required for arguments
- which don't fit in registers. Unlike the PowerOpen ABI, the
- SysV ABI doesn't reserve any extra space for parameters which
- are put in registers. */
- for (argno = 0; argno < nargs; argno++)
+ unsigned char buf[4];
+
+ read_memory (pc, buf, 4);
+ return (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3];
+}
+
+
+/* An instruction to match. */
+struct insn_pattern
+{
+ unsigned int mask; /* mask the insn with this... */
+ unsigned int data; /* ...and see if it matches this. */
+ int optional; /* If non-zero, this insn may be absent. */
+};
+
+/* Return non-zero if the instructions at PC match the series
+ described in PATTERN, or zero otherwise. PATTERN is an array of
+ 'struct insn_pattern' objects, terminated by an entry whose mask is
+ zero.
+
+ When the match is successful, fill INSN[i] with what PATTERN[i]
+ matched. If PATTERN[i] is optional, and the instruction wasn't
+ present, set INSN[i] to 0 (which is not a valid PPC instruction).
+ INSN should have as many elements as PATTERN. Note that, if
+ PATTERN contains optional instructions which aren't present in
+ memory, then INSN will have holes, so INSN[i] isn't necessarily the
+ i'th instruction in memory. */
+static int
+insns_match_pattern (CORE_ADDR pc,
+ struct insn_pattern *pattern,
+ unsigned int *insn)
+{
+ int i;
+
+ for (i = 0; pattern[i].mask; i++)
{
- arg = args[argno];
- type = check_typedef (VALUE_TYPE (arg));
- len = TYPE_LENGTH (type);
-
- if (TYPE_CODE (type) == TYPE_CODE_FLT)
- {
- if (freg <= 8)
- freg++;
- else
- {
- /* SysV ABI converts floats to doubles when placed in
- memory and requires 8 byte alignment */
- if (argstkspace & 0x4)
- argstkspace += 4;
- argstkspace += 8;
- }
- }
- else if (TYPE_CODE (type) == TYPE_CODE_INT && len == 8) /* long long */
- {
- if (greg > 9)
- {
- greg = 11;
- if (argstkspace & 0x4)
- argstkspace += 4;
- argstkspace += 8;
- }
- else
- {
- if ((greg & 1) == 0)
- greg++;
- greg += 2;
- }
- }
+ insn[i] = read_insn (pc);
+ if ((insn[i] & pattern[i].mask) == pattern[i].data)
+ pc += 4;
+ else if (pattern[i].optional)
+ insn[i] = 0;
else
- {
- if (len > 4
- || TYPE_CODE (type) == TYPE_CODE_STRUCT
- || TYPE_CODE (type) == TYPE_CODE_UNION)
- {
- /* Rounding to the nearest multiple of 8 may not be necessary,
- but it is safe. Particularly since we don't know the
- field types of the structure */
- structstkspace += round2 (len, 8);
- }
- if (greg <= 10)
- greg++;
- else
- argstkspace += 4;
- }
+ return 0;
}
- /* Get current SP location */
- saved_sp = read_sp ();
+ return 1;
+}
- sp -= argstkspace + structstkspace;
- /* Allocate space for backchain and callee's saved lr */
- sp -= 8;
+/* Return the 'd' field of the d-form instruction INSN, properly
+ sign-extended. */
+static CORE_ADDR
+insn_d_field (unsigned int insn)
+{
+ return ((((CORE_ADDR) insn & 0xffff) ^ 0x8000) - 0x8000);
+}
- /* Make sure that we maintain 16 byte alignment */
- sp &= ~0x0f;
- /* Update %sp before proceeding any further */
- write_register (SP_REGNUM, sp);
+/* Return the 'ds' field of the ds-form instruction INSN, with the two
+ zero bits concatenated at the right, and properly
+ sign-extended. */
+static CORE_ADDR
+insn_ds_field (unsigned int insn)
+{
+ return ((((CORE_ADDR) insn & 0xfffc) ^ 0x8000) - 0x8000);
+}
+
+
+/* If DESC is the address of a 64-bit PowerPC GNU/Linux function
+ descriptor, return the descriptor's entry point. */
+static CORE_ADDR
+ppc64_desc_entry_point (CORE_ADDR desc)
+{
+ /* The first word of the descriptor is the entry point. */
+ return (CORE_ADDR) read_memory_unsigned_integer (desc, 8);
+}
+
+
+/* Pattern for the standard linkage function. These are built by
+ build_plt_stub in elf64-ppc.c, whose GLINK argument is always
+ zero. */
+static struct insn_pattern ppc64_standard_linkage[] =
+ {
+ /* addis r12, r2, <any> */
+ { insn_d (-1, -1, -1, 0), insn_d (15, 12, 2, 0), 0 },
+
+ /* std r2, 40(r1) */
+ { -1, insn_ds (62, 2, 1, 40, 0), 0 },
- /* write the backchain */
- store_address (old_sp_buf, 4, saved_sp);
- write_memory (sp, old_sp_buf, 4);
+ /* ld r11, <any>(r12) */
+ { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 0 },
- argoffset = 8;
- structoffset = argoffset + argstkspace;
- freg = 1;
- greg = 3;
- /* Fill in r3 with the return structure, if any */
- if (struct_return)
+ /* addis r12, r12, 1 <optional> */
+ { insn_d (-1, -1, -1, -1), insn_d (15, 12, 2, 1), 1 },
+
+ /* ld r2, <any>(r12) */
+ { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 2, 12, 0, 0), 0 },
+
+ /* addis r12, r12, 1 <optional> */
+ { insn_d (-1, -1, -1, -1), insn_d (15, 12, 2, 1), 1 },
+
+ /* mtctr r11 */
+ { insn_xfx (-1, -1, -1, -1), insn_xfx (31, 11, 9, 467),
+ 0 },
+
+ /* ld r11, <any>(r12) */
+ { insn_ds (-1, -1, -1, 0, -1), insn_ds (58, 11, 12, 0, 0), 0 },
+
+ /* bctr */
+ { -1, 0x4e800420, 0 },
+
+ { 0, 0, 0 }
+ };
+#define PPC64_STANDARD_LINKAGE_LEN \
+ (sizeof (ppc64_standard_linkage) / sizeof (ppc64_standard_linkage[0]))
+
+
+/* Recognize a 64-bit PowerPC GNU/Linux linkage function --- what GDB
+ calls a "solib trampoline". */
+static int
+ppc64_in_solib_call_trampoline (CORE_ADDR pc, char *name)
+{
+ /* Detecting solib call trampolines on PPC64 GNU/Linux is a pain.
+
+ It's not specifically solib call trampolines that are the issue.
+ Any call from one function to another function that uses a
+ different TOC requires a trampoline, to save the caller's TOC
+ pointer and then load the callee's TOC. An executable or shared
+ library may have more than one TOC, so even intra-object calls
+ may require a trampoline. Since executable and shared libraries
+ will all have their own distinct TOCs, every inter-object call is
+ also an inter-TOC call, and requires a trampoline --- so "solib
+ call trampolines" are just a special case.
+
+ The 64-bit PowerPC GNU/Linux ABI calls these call trampolines
+ "linkage functions". Since they need to be near the functions
+ that call them, they all appear in .text, not in any special
+ section. The .plt section just contains an array of function
+ descriptors, from which the linkage functions load the callee's
+ entry point, TOC value, and environment pointer. So
+ in_plt_section is useless. The linkage functions don't have any
+ special linker symbols to name them, either.
+
+ The only way I can see to recognize them is to actually look at
+ their code. They're generated by ppc_build_one_stub and some
+ other functions in bfd/elf64-ppc.c, so that should show us all
+ the instruction sequences we need to recognize. */
+ unsigned int insn[PPC64_STANDARD_LINKAGE_LEN];
+
+ return insns_match_pattern (pc, ppc64_standard_linkage, insn);
+}
+
+
+/* When the dynamic linker is doing lazy symbol resolution, the first
+ call to a function in another object will go like this:
+
+ - The user's function calls the linkage function:
+
+ 100007c4: 4b ff fc d5 bl 10000498
+ 100007c8: e8 41 00 28 ld r2,40(r1)
+
+ - The linkage function loads the entry point (and other stuff) from
+ the function descriptor in the PLT, and jumps to it:
+
+ 10000498: 3d 82 00 00 addis r12,r2,0
+ 1000049c: f8 41 00 28 std r2,40(r1)
+ 100004a0: e9 6c 80 98 ld r11,-32616(r12)
+ 100004a4: e8 4c 80 a0 ld r2,-32608(r12)
+ 100004a8: 7d 69 03 a6 mtctr r11
+ 100004ac: e9 6c 80 a8 ld r11,-32600(r12)
+ 100004b0: 4e 80 04 20 bctr
+
+ - But since this is the first time that PLT entry has been used, it
+ sends control to its glink entry. That loads the number of the
+ PLT entry and jumps to the common glink0 code:
+
+ 10000c98: 38 00 00 00 li r0,0
+ 10000c9c: 4b ff ff dc b 10000c78
+
+ - The common glink0 code then transfers control to the dynamic
+ linker's fixup code:
+
+ 10000c78: e8 41 00 28 ld r2,40(r1)
+ 10000c7c: 3d 82 00 00 addis r12,r2,0
+ 10000c80: e9 6c 80 80 ld r11,-32640(r12)
+ 10000c84: e8 4c 80 88 ld r2,-32632(r12)
+ 10000c88: 7d 69 03 a6 mtctr r11
+ 10000c8c: e9 6c 80 90 ld r11,-32624(r12)
+ 10000c90: 4e 80 04 20 bctr
+
+ Eventually, this code will figure out how to skip all of this,
+ including the dynamic linker. At the moment, we just get through
+ the linkage function. */
+
+/* If the current thread is about to execute a series of instructions
+ at PC matching the ppc64_standard_linkage pattern, and INSN is the result
+ from that pattern match, return the code address to which the
+ standard linkage function will send them. (This doesn't deal with
+ dynamic linker lazy symbol resolution stubs.) */
+static CORE_ADDR
+ppc64_standard_linkage_target (CORE_ADDR pc, unsigned int *insn)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
+
+ /* The address of the function descriptor this linkage function
+ references. */
+ CORE_ADDR desc
+ = ((CORE_ADDR) read_register (tdep->ppc_gp0_regnum + 2)
+ + (insn_d_field (insn[0]) << 16)
+ + insn_ds_field (insn[2]));
+
+ /* The first word of the descriptor is the entry point. Return that. */
+ return ppc64_desc_entry_point (desc);
+}
+
+
+/* Given that we've begun executing a call trampoline at PC, return
+ the entry point of the function the trampoline will go to. */
+static CORE_ADDR
+ppc64_skip_trampoline_code (CORE_ADDR pc)
+{
+ unsigned int ppc64_standard_linkage_insn[PPC64_STANDARD_LINKAGE_LEN];
+
+ if (insns_match_pattern (pc, ppc64_standard_linkage,
+ ppc64_standard_linkage_insn))
+ return ppc64_standard_linkage_target (pc, ppc64_standard_linkage_insn);
+ else
+ return 0;
+}
+
+
+/* Support for CONVERT_FROM_FUNC_PTR_ADDR(ADDR) on PPC64 GNU/Linux.
+
+ Usually a function pointer's representation is simply the address
+ of the function. On GNU/Linux on the 64-bit PowerPC however, a
+ function pointer is represented by a pointer to a TOC entry. This
+ TOC entry contains three words, the first word is the address of
+ the function, the second word is the TOC pointer (r2), and the
+ third word is the static chain value. Throughout GDB it is
+ currently assumed that a function pointer contains the address of
+ the function, which is not easy to fix. In addition, the
+ conversion of a function address to a function pointer would
+ require allocation of a TOC entry in the inferior's memory space,
+ with all its drawbacks. To be able to call C++ virtual methods in
+ the inferior (which are called via function pointers),
+ find_function_addr uses this function to get the function address
+ from a function pointer. */
+
+/* Return real function address if ADDR (a function pointer) is in the data
+ space and is therefore a special function pointer. */
+
+static CORE_ADDR
+ppc64_linux_convert_from_func_ptr_addr (CORE_ADDR addr)
+{
+ struct obj_section *s;
+
+ s = find_pc_section (addr);
+ if (s && s->the_bfd_section->flags & SEC_CODE)
+ return addr;
+
+ /* ADDR is in the data space, so it's a pointer to a descriptor, not
+ the entry point. */
+ return ppc64_desc_entry_point (addr);
+}
+
+
+enum {
+ ELF_NGREG = 48,
+ ELF_NFPREG = 33,
+ ELF_NVRREG = 33
+};
+
+enum {
+ ELF_GREGSET_SIZE = (ELF_NGREG * 4),
+ ELF_FPREGSET_SIZE = (ELF_NFPREG * 8)
+};
+
+void
+ppc_linux_supply_gregset (char *buf)
+{
+ int regi;
+ struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
+
+ for (regi = 0; regi < 32; regi++)
+ supply_register (regi, buf + 4 * regi);
+
+ supply_register (PC_REGNUM, buf + 4 * PPC_LINUX_PT_NIP);
+ supply_register (tdep->ppc_lr_regnum, buf + 4 * PPC_LINUX_PT_LNK);
+ supply_register (tdep->ppc_cr_regnum, buf + 4 * PPC_LINUX_PT_CCR);
+ supply_register (tdep->ppc_xer_regnum, buf + 4 * PPC_LINUX_PT_XER);
+ supply_register (tdep->ppc_ctr_regnum, buf + 4 * PPC_LINUX_PT_CTR);
+ if (tdep->ppc_mq_regnum != -1)
+ supply_register (tdep->ppc_mq_regnum, buf + 4 * PPC_LINUX_PT_MQ);
+ supply_register (tdep->ppc_ps_regnum, buf + 4 * PPC_LINUX_PT_MSR);
+}
+
+void
+ppc_linux_supply_fpregset (char *buf)
+{
+ int regi;
+ struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
+
+ for (regi = 0; regi < 32; regi++)
+ supply_register (FP0_REGNUM + regi, buf + 8 * regi);
+
+ /* The FPSCR is stored in the low order word of the last doubleword in the
+ fpregset. */
+ supply_register (tdep->ppc_fpscr_regnum, buf + 8 * 32 + 4);
+}
+
+/*
+ Use a local version of this function to get the correct types for regsets.
+*/
+
+static void
+fetch_core_registers (char *core_reg_sect,
+ unsigned core_reg_size,
+ int which,
+ CORE_ADDR reg_addr)
+{
+ if (which == 0)
{
- char val_buf[4];
- store_address (val_buf, 4, struct_addr);
- memcpy (®isters[REGISTER_BYTE (greg)], val_buf, 4);
- greg++;
+ if (core_reg_size == ELF_GREGSET_SIZE)
+ ppc_linux_supply_gregset (core_reg_sect);
+ else
+ warning ("wrong size gregset struct in core file");
}
- /* Now fill in the registers and stack... */
- for (argno = 0; argno < nargs; argno++)
+ else if (which == 2)
{
- arg = args[argno];
- type = check_typedef (VALUE_TYPE (arg));
- len = TYPE_LENGTH (type);
-
- if (TYPE_CODE (type) == TYPE_CODE_FLT)
- {
- if (freg <= 8)
- {
- if (len > 8)
- printf_unfiltered (
- "Fatal Error: a floating point parameter #%d with a size > 8 is found!\n", argno);
- memcpy (®isters[REGISTER_BYTE (FP0_REGNUM + freg)],
- VALUE_CONTENTS (arg), len);
- freg++;
- }
- else
- {
- /* SysV ABI converts floats to doubles when placed in
- memory and requires 8 byte alignment */
- /* FIXME: Convert floats to doubles */
- if (argoffset & 0x4)
- argoffset += 4;
- write_memory (sp + argoffset, (char *) VALUE_CONTENTS (arg), len);
- argoffset += 8;
- }
- }
- else if (TYPE_CODE (type) == TYPE_CODE_INT && len == 8) /* long long */
- {
- if (greg > 9)
- {
- greg = 11;
- if (argoffset & 0x4)
- argoffset += 4;
- write_memory (sp + argoffset, (char *) VALUE_CONTENTS (arg), len);
- argoffset += 8;
- }
- else
- {
- if ((greg & 1) == 0)
- greg++;
-
- memcpy (®isters[REGISTER_BYTE (greg)],
- VALUE_CONTENTS (arg), 4);
- memcpy (®isters[REGISTER_BYTE (greg + 1)],
- VALUE_CONTENTS (arg) + 4, 4);
- greg += 2;
- }
- }
+ if (core_reg_size == ELF_FPREGSET_SIZE)
+ ppc_linux_supply_fpregset (core_reg_sect);
else
- {
- char val_buf[4];
- if (len > 4
- || TYPE_CODE (type) == TYPE_CODE_STRUCT
- || TYPE_CODE (type) == TYPE_CODE_UNION)
- {
- write_memory (sp + structoffset, VALUE_CONTENTS (arg), len);
- store_address (val_buf, 4, sp + structoffset);
- structoffset += round2 (len, 8);
- }
- else
- {
- memset (val_buf, 0, 4);
- memcpy (val_buf, VALUE_CONTENTS (arg), len);
- }
- if (greg <= 10)
- {
- *(int *) ®isters[REGISTER_BYTE (greg)] = 0;
- memcpy (®isters[REGISTER_BYTE (greg)], val_buf, 4);
- greg++;
- }
- else
- {
- write_memory (sp + argoffset, val_buf, 4);
- argoffset += 4;
- }
- }
+ warning ("wrong size fpregset struct in core file");
}
-
- target_store_registers (-1);
- return sp;
}
-/* This version of ppc_linux_memory_remove_breakpoints handles the
- case of self modifying code */
-int
-ppc_linux_memory_remove_breakpoint (CORE_ADDR addr, char *contents_cache)
-{
- unsigned char *bp;
- int val;
- int bplen;
- char old_contents[BREAKPOINT_MAX];
+/* Register that we are able to handle ELF file formats using standard
+ procfs "regset" structures. */
- /* Determine appropriate breakpoint contents and size for this address. */
- bp = BREAKPOINT_FROM_PC (&addr, &bplen);
- if (bp == NULL)
- error ("Software breakpoints not implemented for this target.");
+static struct core_fns ppc_linux_regset_core_fns =
+{
+ bfd_target_elf_flavour, /* core_flavour */
+ default_check_format, /* check_format */
+ default_core_sniffer, /* core_sniffer */
+ fetch_core_registers, /* core_read_registers */
+ NULL /* next */
+};
+
+static void
+ppc_linux_init_abi (struct gdbarch_info info,
+ struct gdbarch *gdbarch)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
- val = target_read_memory (addr, old_contents, bplen);
+ /* Until November 2001, gcc was not complying to the SYSV ABI for
+ returning structures less than or equal to 8 bytes in size. It was
+ returning everything in memory. When this was corrected, it wasn't
+ fixed for native platforms. */
+ set_gdbarch_use_struct_convention (gdbarch,
+ ppc_sysv_abi_broken_use_struct_convention);
- /* If our breakpoint is no longer at the address, this means that the
- program modified the code on us, so it is wrong to put back the
- old value */
- if (val == 0 && memcmp (bp, old_contents, bplen) == 0)
- val = target_write_memory (addr, contents_cache, bplen);
+ if (tdep->wordsize == 4)
+ {
+ /* Note: kevinb/2002-04-12: See note in rs6000_gdbarch_init regarding
+ *_push_arguments(). The same remarks hold for the methods below. */
+ set_gdbarch_frameless_function_invocation (gdbarch,
+ ppc_linux_frameless_function_invocation);
+ set_gdbarch_deprecated_frame_chain (gdbarch, ppc_linux_frame_chain);
+ set_gdbarch_deprecated_frame_saved_pc (gdbarch, ppc_linux_frame_saved_pc);
+
+ set_gdbarch_deprecated_frame_init_saved_regs (gdbarch,
+ ppc_linux_frame_init_saved_regs);
+ set_gdbarch_deprecated_init_extra_frame_info (gdbarch,
+ ppc_linux_init_extra_frame_info);
+
+ set_gdbarch_memory_remove_breakpoint (gdbarch,
+ ppc_linux_memory_remove_breakpoint);
+ /* Shared library handling. */
+ set_gdbarch_in_solib_call_trampoline (gdbarch, in_plt_section);
+ set_gdbarch_skip_trampoline_code (gdbarch,
+ ppc_linux_skip_trampoline_code);
+ set_solib_svr4_fetch_link_map_offsets
+ (gdbarch, ppc_linux_svr4_fetch_link_map_offsets);
+ }
+
+ if (tdep->wordsize == 8)
+ {
+ /* Handle PPC64 GNU/Linux function pointers (which are really
+ function descriptors). */
+ set_gdbarch_convert_from_func_ptr_addr
+ (gdbarch, ppc64_linux_convert_from_func_ptr_addr);
+
+ set_gdbarch_in_solib_call_trampoline
+ (gdbarch, ppc64_in_solib_call_trampoline);
+ set_gdbarch_skip_trampoline_code (gdbarch, ppc64_skip_trampoline_code);
+ }
+}
- return val;
+void
+_initialize_ppc_linux_tdep (void)
+{
+ gdbarch_register_osabi (bfd_arch_powerpc, 0, GDB_OSABI_LINUX,
+ ppc_linux_init_abi);
+ add_core_fns (&ppc_linux_regset_core_fns);
}
projects / deliverable / binutils-gdb.git / blobdiff